This invention lies in a highly developed area of the art relating to apparatus for facilitating the loading and unloading of vehicles and the handling of loads within the confines of the vehicles. For the most part, the prior art apparatus provides means whereby loads are actually lifted off of the supporting surface and transferred either into or out of the vehicle. Accordingly, the power and structural requirements of such apparatus are extremely high if the apparatus is to operate efficiently for any substantial period of time. The purpose of this invention is to provide a more simplified apparatus for loading and unloading vehicles having minimum power and structural requirements. Under the general concept of the invention, power-driven cables are stretched over the vehicle floor from front to rear and are movable in either direction in unison. A plurality of cables are used and spaced laterally of the vehicle. The number of cables which are to be used depends upon the size and type load to be handled. The loads are placed directly on the cables and the cables are actuated to shift the loads from front to rear or vice versa as the case may be. The cables ride on the vehicle floor, however, the frictional contact is only a line contact and is substantially less than the contact which would occur if the loads were placed directly on the floor.
At least one other in the prior art has designed a similar system for vehicles. This system is disclosed in U.S. Pat. No. 3,272,358, entitled TRUCK UNLOADING STRUCTURE, dated Sept. 13, 1966, to F. Thompson. Thompson discloses the general concept of using cables on a vehicle floor to shift loads therein. However, it is quite apparent that his arrangement has little utility except for relatively small loads. Thompson employs a plurality of endless cables stretched over a friction surface roll and idlers rolls. The friction roll is driven by a suitable power source. It is quite apparent, however, that the frictional contact between the roll and cable is not sufficient to move loads of any appreciable size and weight. Further, Thompson's particular arrangement of pulleys for supporting the cables is unsuitable for use in trailers having fifth wheel assemblies thereon.
Other arrangements found in the prior art use movable floors or the like comprising flexible planar sheets or floors covering substantially the entire area of the vehicle load-supporting floor. The sheets are wound onto takeup reels positioned on the vehicle. The deficiencies of this arrangement are quite apparent in that use of such a movable sheet or the like provides no relief from substantial frictional contact with the underlying floor of the vehicle. The cables of this invention as mentioned above provide substantially line frictional contact, which is substantially less than that which would be experienced with the use of the movable sheet referred to above. Further, the movable sheet-type arrangements are cumbersome and do not lend themselves to ready adaptability to existing truck bodies, and are likewise unsuitable for use with trailers having fifth wheel coupling assemblies. Further, the apparatus of the prior art generally renders the vehicle inoperative for unloading by a forklift truck, for example, wherein the truck must enter the vehicle. The cable arrangement of this invention cannot be damaged by driving a forklift across the vehicle floor and over the cables.
An objective of this invention is to provide a simplified loading and unloading apparatus for vehicles requiring a relatively low power output for efficient operation.
Further, it is an objective of this invention to provide a loading and unloading apparatus which may be readily installed in existing truck bodies with a minimum of modifications to the truck body.
It is another objective of this invention to combine with a cable type loading and unloading apparatus of this invention a movable bulkhead which is affixed to the cables and movable therewith to assist in pushing loads to the rear of the vehicle, especially lighter loads.
Another objective of this invention is to provide separate power outputs for opposite ends of the cables with each of the outputs having reels or sheaves for receiving the cables. The reels of each power output alternately serve as supply or takeup reels depending upon which power output is energized. This is turn determines the direction of movement of the cables on the vehicle floor.
It is another objective of this invention to provide a loading and unloading apparatus which may be marketed in a compact package and readily installed by the vehicle owner.
It is a further objective of this invention to provide a loading and unloading apparatus having a minimum of parts including the load-supporting cables, the bulkheads, a set of pull-back cables, a power unit including the separate power outputs and separate sets of reels, and the miscellaneous pulleys used to properly space and guide the cables.